Process and apparatus for contacting two materials



Feb. 4,v 'I L EfgvvlLsoN y 2,029,688

1 PROCESS ANDIAPPARATUS RoR oNmAcT-INGTWO 'MATERIALS Filed nec. s. 1932y 'ATTORNEY Patented Feb. 4, 1936 -g raoonss AND APPARATUS FonooN'rAc'rme 'rwo MATERIALS neben E. wilson, emes", n1., einer testandard Oil Company, Chicago, Ill., a corporation of IndianaApplication December Vs, 1932, serial 1m64.553s

6 Claims,

My. invention relatesto processes and apparatus for the continuouscounter-current con-- tactlng of two materials, particularly twosubstantially liquid materials. More particularly it relates toprocesses and apparatus for the continuous counter-current extraction ofa mineral lubricating oil stock with a selective solvent.

It is an object of my invention to provide a e more eficient, effectiveand economical process 10 and apparatus for' continuous counter-currentcontacting of this type than any heretofore available. In particular itis my object to provide a novel and advantageoustype yof process andapparatus for the continuous counter-current extraction of a minerallubricating'oil stock with a selective solvent. The various detailedobjects of my invention will lbecome apparent as the description thereofproceeds.

Mineral lubricating Aoil stocks, particularly `20 mixed base stocks, asproduced by distillation processes from crude mineral oils contain agreat variety of chemical constituents most of which.

have never been indlviduallyidentiiied but which may be roughly classiedas relatively parafdnic" 35 thenic constituents and will be referred toherein as a relatively naphthenic fraction. In general, the'relativelyparamnic fraction can be identitled as having a high ratio of hydrogento carbon,.a low temperature coelcient of-viscosity,

40 and a high resistance to sludging as compared -with the relativelynaphthenic fraction.-

Itis well known that the relatively parailinic constituents arepreferable to either the relatively'` naphthenic constituents or theoriginal 45 mineral lubricating oil stock for use as an ordinarylubricant. For this reason many attempts have been made to'separatethese relatively paraflinic constituents from the accompanyingrelatively naphthenic constituents in order to produce 50 a superiorlubricating oil. jIn the past this has frequently beendone by extractingthe mineral lubricating oil .stock with a selectivesolvent for eitherthe relatively paramnic constituents or the relatively naphthenicconstituents, generally the 66 letter.

The principal procedures which have been used in this type of process todate have been:

1. More or less completely dissolving the lubricating oil stock in asolvent at an elevated temperature and then lowering the temperature so5 as to throw a relatively parainic fraction out of solution as aseparate liquid phase; and

2. Agitating .the mineral lubricating oilstock with a solvent in a tankor similar vessel at such a temperature vthat a fraction (generally the10 relatively naphthenic fraction) is dissolved and the remainingfraction is left as a separate liquid phase.

The process and apparatus of my invention improve on these prior artpractices by passing 15 the` mineral lubricating oil stock and aselective solvent in counter-current relationship to each other and incontinuous or preferablyintermittent contact with each other,coagitating them throughout an intermediate portion of their contactzone and removing the resultant materials, which are, in general: (l)the bulk of the selective solvent carrying with it in solution a rela*--tively naphthenic fraction of the original mineral lubricating oilstock, and (2) the residual g5 relatively paratllnic fraction carryingwith it some dissolved solvent and generally some entrained material. Myprocess has the advantage of continuity. requires very little equipmentfor a plan of large capacity, is very cheap as compared with formerprocesses, is much more ilexible andecontrollable than the prior artbatch processes and accomplishes a more eilicient extraction, i. e.,there is more divergence in properties between the relatively parafllnicand the relatively naphthenic fractions as I produce them than betweenthe corresponding fractions as pro.- duced by the prior art processeslwith which I f am familiar.

Reference will now be had more particularly 40 to the drawing in which:Figure 1 represents a longitudinal view of my apparatus, partly'insection; and Figure 2 represents a partial trans- -described later. Anupwardly elongated settling chamber similar to sump I2 may, if desired,be used at the end of chamber Il opposite sump I2 and the pipecontrolled by valve 29 may suitably lead o!! from a point near the topof said up- Il tal, as indicated in the drawing. Chamber Il.

may be of any suitable cross section, for instance circular (as shown),U -shaped or elliptical with the vertical axis longer than thehorizontal. At

the end of the chamber II, which carries the sump I2, a pipe I3 entersthe chamber and is upturned to permit the introduction oi a fluidmaterial to chamber II in an upwardly-directed stream. 'I'he uptumed endoi' pipe I3 is shown as carrying a perforated baule I4 adaptedto'distribute the incoming material. At the opposite end of chamber Il apipe I8 enters .the chamber at the' bottom thereof and a pipe I1 entersat the top, one or both of which are used for the introduction of thesecond material to be contacted. M; I

As a specic embodiment of my invention, I utilize my process andapparatus to extract a mineral lubricating oil stock, namely, awaxbearing cut made by distillation of a Mid- Continent crude oil andhaving a viscosity of 74 seconds Saybolt at 210 F., with a selectivesolvent, namely, dichlorethylether. Since the solvent has a higherspecific gravity than the lubricating oil stock it flows through myapparatus as a lower stratum and the lubricating oil stockilows in theopposite direction as an upper stratum.

If my process is operatedk without rotation of shaft I8 carrying paddlesI9 the operation is as follows: The dichlorethylether is introducedthrough pipe I E, is deflected by baiile 20 and passes along the bottomof chamber I I through passages f 23 which are formed by chamber Illandbailles 24. Dichlorethylether may also, or alternatively, be admittedthrough pipe I1 by means of pipe 21| and valve 22 and if so it ilowsdownwardly through the outgoing stream of extractedlubri` eating oilstock, thereby Washing out at least a portion of the entrained dirtydichlorethylether carried by said extracted lubricating oil stock,passing to the bottom of chamber II and ilowing through passages 23 insuccession along with the dichlorethylether, if any, admitted throughpipe I6. The dichlorethylether (carrying extractedrelatively naphthenicconstituents of the original lubricating oil stock) ows out through thelast passage 23 on the right and comes in contact with the incominglubricating oil stock introduced through pipe I3. 'Ihis is desirablesince this incoming stock is often highly viscous and by allowing it todissolve a portion of the solvent its viscosity is reduced and it flowsthrough the apparatus more readily than would otherwise be the case. Thespent" dichlorethylether then passes into sump I2 which is elongated topermit entrained undissolved oil to settle out and the settleddichlorethylether `with the dissolved Vrelatively naphthenic fraction isremoved from sump I2 through pipe 25 and valve 26. The material removedthrough pipe 25 is then subjected to a fractional distillation operationto remove the dichlorethyletherA from the relatively naphthenic fractionof the lubricating oil stock dissolved therein. The dichlorethylether,after purification, if desired, is then returned to the process throughpipe I6 and/or pipe I1 .andthe relatively naphthenic fraction isavailable as a by-product.

Simultaneously with the introduction of dichlorethylether through pipeI6 and/or pipe I1, lubricating oil stock is introduced through pipe,oaaessv I3, preferably at about one-half the rate at which thedichlorethvlether is introduced. lThe lubrieating oil stock, afterpicking up some ofthe spent dichlorethylether as previously described,flows upwardly through compartment -2l I`and thence in successionthrough passages 21 formed by chamber II and bailes 24. Flowing out oi'the last passage 21. on the left it comes in contact with lireshdichlorethylether introduced through pipe I1, passes under bame 23(which is used to preserve qulescence in the vicinity ofthe outlet) andis continuously removed from chamber Il through valve 23. y

Bames 24 in their preferred form extendtransversely across chamber IIa'nd serve to divide it into a series of compartmentsv including endcompartments 2 9 and intermediate compartments 30. As hereinbeforementioned, bales 24 do not extend to the top or bottom of chamber II butare cut oil to form segmental passages 23 and 21 at the bottom and toprespectively. In other suitable forms of my apparatus, these passagesmay be formed by openings located near the top and bottom of baiiles 24and may be staggered so that passages in adjacent baiiles are not inalignment and material owing through them must therefore pursue acircuitous course.4 When working with highly viscous materials,it issometimes desirable to use circular passages and to place a small screwconveyor in each passage, or in certain of them to expedite the dow ofmaterial. y

In the center of each compartment 3l are located two secondary bailies3l extending downwardly from the top of chamber I I and upwardly fromthe bottom thereof. respectively. These baiiies 3l are preferablycircular segments as shown and it is preferred that they extend topoints considerably closer to the axis of chamber II than do passages 23and 21. The purpose of baffles 3| is to force the materials flowingthrough chamber II to pass into the central portion of chamber II atintervals throughout their flow. Extending throughout the length ofchamber II and approximately axially disposed therein is shaft I8 whichis carried by bearings 32 as shown. Shaft I8 is driven through pulleywheels 33 and belt 34 by means of drive shaft 35 which is rotated bymeans not shown. The speed of rotation of shaft I8 can be varied at willby changing the position of belt 34 on pulley wheels 33. Any suitablemeans for selectively adjusting the speed of rotation of shaft 35 can beused but it is highly important that some such means be provided. Withineach half of each of compartments 33, shaft I8 carries a paddle I3suitably mounted to rotate with shaft I8. Paddles I9, as shown,

` and slightly reduced agitation at points progressively nearer to theperiphery of chamber Il. It is preferred that the blades of paddles I3,when in vertical/position, extend somewhat closer to the top and bottomof chamber II than do the inner edges of bailles 3l but not as close asdo the outer edges of bailies 24.

Various modifications can be made in paddles I3. In some cases it isdesirable to perforate them so as to obtain an increased emulsifyingeffect. A still higher degree of agitation can, when desired, beobtained by using a greater number of blades on each Wheel and/ or bymaking the blades cup-'shaped rather than nat.

Having now described the principal characteristics of my process andapparatus with the exception of the centrifugal'separation feature to bedescribed later, I will turn now to a more detailed discussion oftheflow of materials through chamber Il. scribed above I have indicated theiiow of materials when no agitation is used, i. e., when shaft Il andpaddles I 9 are stationary. Under such conditions, however, there islittle effective extraction because thecontact between thedichlorethylether. andthe lubricating oil stock is entirely inadequate.By rotating paddles ilat a moderate speed, generally within Vthe range 8to 50 R.. P. M., it is possible to create a well mixed emulsiiiedstratum in the central part ofthe apparatus, quite adequate to giveeifective contact, and yet by having the paddles fairly short, as shown,continuous separation of the two materials in each of compartments lllcan be obtained. The result of operating under such conditions is thatthere is always a stratum ofsubstantially unemulsified lubricating oilstock at the top of each of the compartments, 'a stratum ofsubstantially unemulsiiied dichlorethylether at the bottom ofeach of thecompartments and an intermediate well-mixed or emulsiiled layer. As

. aforementioned, the upper limit of the emulsiiied layer should beabove the lower edges of the upperfbaiiles 3i and below the upper edgesof batlies 24 and the corresponding lower limit should be below theupper edges of bailles 3| and above the 'lower edges of the lower bames2l. By adjusting the speed of rotation of shaft i8v in order to achievethis result it is possible to prevent any lubricating oil stock anddichlorethylether in each contact zone of my process(i. e., in each ofcompartments 30)' by soV adjusting the rate of introduction of thestarting materials as to make the time of contacting Lin each stageabout two to four minutes. By using 5 or 6 stages I obtain an extremelyefilcient countercurrent extraction such as could be secured only by agreat many separate and time-consuming lsteps when. using Y the oldprior art processes.

\'.I'he.rate of rotation of shaft I8 which will accomplish this desiredoptimum degree of emulsiiication will vary greatly with such factors asthe character of the materials being contacted, the temperature, thedesign of the paddles, etc. butin typical cases it will be within therange 5 to 60 R. P. M.

My apparatus can` be designed to have any number of compartments 30 fromone up. However, in order to take full advantage of the counter-currentprinciple, I prefer ,to use atleast three compartments 3l, andpreferably four or iive of them in addition vto the two end compartments29. In general .it is not-desirable to use ymore than six compartmentssince the advantage lgained by theaddition of further compartments isnot sufficient to ofiset the additional cost.

A further feature of my process and apparatus, which has not heretoforebeen discussed, is a method for removing entrained material from one orboth of the resultant materials withdrawn from chamber I i. yThe drawingshows this .re-

`In the specific embodiment de'- moval of entrained material asoperating on the lighter of the two resultant materials leaving chamberII. In the speciiic embodiment heretofore referred to, this lightermaterial is the extracted lubricating oil stock, i. e., the relativelyparafiinic fraction together with some dissolved dichlorethylether andsome entrained material. Rather than subject this whole system, aswithdrawn from chamber II, to distillation to separate dichlorethyletherfrom oil as would normally be done, I prefer to rst remove the entrainedvmaterial since this is composed for the most part of dirtydichlorethylether carrying some of the relatively naphthenicconstituents of the original lubricating oil stock which it is desiredto segregate from the relatively paramnic constituents constituting thebulk of the material removed through valve 28; According to my process,this separation of entrained material is done bythe use of centrifuge $6operated through pulley Il by means of a motive source not shown. 'I'herelatively paralnic fraction produced inf` chamber il carrying somedissolved solvent and some entrained dirty" solvent is withdrawn fromcasing I I through valve 29 and passed to centrifuge 36 'where' theentrained material is separated from the relatively parafiinic fractioncontaining dissolved solvent and said entrained material is returned bymeans of pipe 38, and, if necessary, a suitable pump not shown, tocasing il through valve 39 and/or valve 40. The relatively paraiiinicfraction carrying dissolved solvent passes out of centrifuge 36 throughpipe 4I and is then, in general, subjectedI to fractional distillation,by means not shown, to separate the dichlorethylether from therelatively paraillnic vfraction whichconstitutes the principal finalproduct of my process. The dichlorethylether removed from thisrelatively parafllnic fraction,

after purification if required, is returned to the process by means ofpipe 2| along with the solvent recovered from the relatively naphthenicfraction and fresh "make-up solvent.

As aforementioned, the entrained matter, i. e.,

" dirty solvent separated by centrifuge 36 is returned tcchamber iithrough valve 39 or III. In order to preserve equilibrium conditions inAchamf ber II and to achieve maximum eiilciency it is desirable that thisdirty solvent be returned to chamber Il ata point at which itscomposition,

-containing solvent and relatively naphthenic .lubricating oilconstituents without materially disturbing the equilibrium which existsat the point of introduction between solvent, relatively paraiilnicconstituents and relatively naphthenic constituents. This can be done byadmitting the ,dirty solvent through valve 39 and/or valve III,

depending on which point corresponds more closely. to the compositionofthe dirty solvent. Further alternative points of admission can. ofcourse, be provided as required.

It will be understood that my process can vreadl admitting it to myprocess.

In the foregoing speciilc embodiment I have described the use ofdichlorethylether in my process and apparatus as a desirable selectivesolvent. It will readily be comprehended, however, that a variety ofother solvent materials can satisfactorily be used, the main requirementbeing a selective solvent power for the relatively parafnic constituentsor for the relatively naphthenic constituents of the originallubricating oil stock and a. specific gravity substantially differentfrom that of the. lubricating oil stock to be treated. In

general, it is the relatively napnthenic constituents which areselectively dissolved. As alternatives to the use of dichlorethylfrther, I i'lnd that nltrobenzene and phenol, a* Jong other substances,are very satisfactory in a solvent extraction process of this type. Whenoperating on a wax-bearing lubricating oil stock I can either remove thewax before the'solvent extraction or solvent extract the wax-bearingoil. In thelatvter cases it is sometimes lnecessary to expeditelubricating oil stock, my apparatus can readily be modified to permitthis, the onlyessential difference being that the relative positions ofthe two strata are reversed.

Although in general the introduction of and removal of material from myapparatus should be such as to keep the interface -between the twocounter-current streams substantially in the center of chamber Il, itwill be apparent that this can be adjusted to any other level ifdesired. Thus, for instance, if one of the two materials separates morereadily from the central emulsifled stratum than does the other, it isdesirable to have at any given time in chamber il less ofthe'material'which separates more readily and more of the material whichseparates less readily, the result being that the separation of thelatter is promoted. Therelative amounts of the two materials in chamberIl at any given vtime can readily be controlled by an adjustablefloat-controlled mechanism operating on one or more of the valvescontrolling the admission and/or removal of materials from my apparatus.Suitably this may consist of a device intermediate in density betweenthe two materials in sump I2 which will oat at the interface and controlthe operation of say, valve 26 so as to keep the interfacial level atany desired point.

Although I have described my invention with particular reference to thesolvent extraction of mineral lubricating oil stocks it will readily beunderstood that it may in whole or in part be applied to any process inwhich it is desired to contact `two immiscible or' partially miscibleliquids, or other materials which can be owed. Thus, for example, myprocess and apparatus can be used in the solvent extraction of vegetableoils, solvent extraction of motor fuels, the chemical treatment ofvarious liquids with various reagents, the washing of liquids, etc. I donot, therefore, desire to be limited by my specic disclosure but only bythe appended claims in which I have defined the novel features of my Iclaim:

1. A process for the counter-current contacting of ,two liquidscomprising introducing one of said two liquids into an end contact zoneforming one'of a series of at least ilve adjacent linearly disposedcontact zones, introducing the other of said two liquids intolthe endcontact zone of said series of contact zones located opposite saidrstmentioned end contact zone, iiowing each. of said two liquids througheach of said Contact zones in succession in a direction opposed to thedirec` tion of flow of the otherof said two materials,

separating said two liquids from each other at.

eachof the borders between each adjacent pair ofv said contact zones,partially emulsifying all of the liquid passing through each of theintermediate contact zones, and separately withdrawing two resultantliquids from opposite end contact zones.

2. A process forjthe counter-current extraction of a mineral lubricatingoil stock comprising relatively paraiiinic constituents and relativelynaphthenic constituents with a'selective solvent for said relativelynaphthenic constituents, comprising flowing said lubricating oil stockand said. selective solvent in counter-current relationship to eachother, washing the extracted lubricating oil stock by admitting at leasta part of said selective solvent at a point near the point of withdrawalof, said extracted lubricating oil stock, separately withdrawing theselective solvent after extraction of said relatively naphthenicconstituents, separating said relatively naphthenic constituents fromsaid selective solvent and returning said selective solvent to theprocess, centrifuging the resultant lubricating oil stock to removeentrained dirty solvent and returning said dirty solvent to the processat a point at which the degree of extraction is approximately thatrepresented by the composition of the dirty solvent.

3. In apparatus for the countercurrent contacting of two liquids, agenerally horizontal elongated chamber, a series of transverse baiilesprovided with openings at their tops and bottoms, said bafilespartiallydividing said chamber into two end'compartments and a plurality ofintermediate compartments, said passages which permit liquid strata atthe top andA bottom of said chamber to flow from one of saidcompartments to the next, a second series of transverse bailles, thevmembers thereof located between the members of said first mentionedseries of baiiles and extending upward from the bottom of said chamberand downward from the top of said chamber, agitation means locatedwithin and confined to said intermediate compartments, means forintroducing one of said two liquids into one of said end compartments,means for introducing the other of said two liquids into the other ofsaid end compartments and means for withdrawing a resultant liquid fromeach of saidend compartments.

4. In apparatus for the countercurrent contacting of two liquids agenerally horiontal elongated chamber, a series of bailles, the membersthereof extending downward from the top of said chamber at intervalsalong its length, passages located in the upper portions of the membersof said series of bailies, a second series of bailles, the membersthereof located in staggered relation to the members of saidfirst-mentioned series of bailles at intervals along the length of saidchamber and extending upward from the center of said chamber to pointsabove the lowest points to which the members of said first-mentionedseries of baiiies extend, but not extending to the top of said chamber,a third series of bailles, the members thereof extending upward from thebottom of said chamber at intervals along its length, passages locatedin the lower portions of the members of said third series of baiiles, afourth series of bailles, the members thereof located in staggeredrelation to the members of said third series of battles at intervalsalong the length of said chamber and extending downward from the centeroi said chamber to points below the highest points to which the membersof said third series of baiiies extend, but not extending to the bottomof said chamber, agitation means located within at least some of thespaces between said various baiiles and means for introducing said twoliquids near opposite ends of said chamber and means for withdrawing aresultant liquid near each end of said chamber.

5. In apparatus for theA counter-current contacting of two liquids, agenerally horizontal elongated chamber, a series of transverse baiilesprovided with openings at their tops and bottoms,

said batiles dividing said chamber into two end compartments and atleast three intermediate compartments, said compartments communicat-`ing with each other through said passages which chamber, the members ofsaid last-mentioned series of baffles located between the members ofsaid first-mentioned series of bailies, rotary agitation means locatedwithin and conned to said intermediate compartments, means forselectively adjusting the rate of rotation of said agitation means,means for introducing one of said two liquids into one of said endcompartments, means for introducing the other of said two liquids intothe other of said end compartments, and means for withdrawing aresultant liquid from each of said two end compartments.

6. A process for the counter-current extraction of an oil stockcomprising relatively parainic constituents and relatively naphthenicconstituents with a selective solvent for said relatively naphthenicconstituents, comprising flowing said oil stock and said selectivesolvent in countercurrent relationship to each other, washing theextracted oil stock by admitting at least a part of said selectivesolvent at a point near the point of Withdrawal of said extracted oilstock, separately withdrawing the selective solvent after extraction ofsaid relatively naphthenic constituents, separating said relativelynaphthenic constituents from said selective solvent and returning saidselective solvent to the process, separating the resultant oil stockfrom entrained dirty solvent and returning said dirty solvent totheprocess at a point at which the degree of extraction is approximatelythat represented by the composition of the dirty solvent.

ROBERT E. WILSON.

s'R'rnrrcuvr4 or CORRECTION.

'atent No. 2,029,688. j February 4, 1936.

ROBERT E, WELSON,

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 4,second column, line 48, claim 3, after the comma and before "said"insert the words said compartments communicating with each otherthrough; and lines 68, 69 and 70, claim 4, strike out the words andcomma "passages located in the upper 4,portions of the members of saidseries of baffles, page 5, first column, lines 5 ,6 and '7, claim 4,strike out the words and comma "passages located n the lower portions ofthe members of said third series of baffles, and

that thel said Letters Patent should be read with these correctionstherein that the' same may conform to the record of the case in thePatent Office.

Signed and sealed this 7th day or April, A. D. 1936.

Leslie Frazer Seal) Acting Commissioner of Patents.

